High voltage circuit breaker with two arcing contacts which can be actuated in an opposite direction

ABSTRACT

A high-voltage circuit breaker is described having arcing contacts, which can be driven in opposite directions, as well as corner gears that are coupled, via a driving rod, with the driven insulating nozzle surrounding the arcing contacts, with the corner gears being designed as a lever mechanism using a two-armed control lever. The one end of the control lever is shaped like a fork, with a journal that is attached to the driving rod engaging with this end. The other end of the control lever is coupled, via a reciprocating element, with the head piece of the second arcing contact, which is driven in the opposite direction.

FIELD OF THE INVENTION

The present invention relates to high-voltage circuit breakers andprovides the structural design of the drive mechanism that moves theauxiliary contacts, used for arc quenching, in opposite directions.

BACKGROUND INFORMATION

In circuit breakers, the two coaxially opposite auxiliary contacts,frequently referred to as arcing contacts, are coaxially surrounded bytwo permanent-current contacts, one of which is stationary and the otherdesigned to move in an axial direction. Circuit breakers of this typeusually work with a gaseous quenching agent that flows through the areaseparating the contacts during switching and whose flow can beinfluenced by special compression chambers and nozzles. Among otherthings, an insulating nozzle that is located within thepermanent-current contacts, surrounds the arcing contacts, and can bepermanently connected to both the drivable permanent-current contact andthe driven arcing contact, is used for this purpose.

In a conventional circuit breaker of this type, as described in, forexample, European Patent No. 0 313 813, a driving element is attached tothe insulating nozzle, which transmits the driving movement of thedriven permanent-current contact to the second arcing contact via cornergears in such a way that the two arcing contacts are driven in oppositedirections. For this purpose, the second arcing contact is inserted intoa sliding contact. In the known corner gears, the driving element isdesigned as a gear rack that acts upon the second arcing contact, whichis also designed as a gear rack, via a gear wheel. The driving movementof the insulating nozzle is transmitted linearly onto the second arcingcontact being driven in the opposite direction. Alternatively, thecorner gears can also be a locking mechanism having a ratchet gear thatis moved by the driven contacts and a clamping part equipped with acompression spring, with the clamping part driving the arcing contactmoving in the opposite direction in a pulsating manner after a ratchetclears the ratchet gear.

In another conventional circuit breaker of this type, a crank can alsobe used as the corner gear, with its rotating part being formed by thegear wheel that is driven by the gear rack connected to the insulatingnozzle, as described in, for example, European Patent No. 0 696 040. Thelinear movement of the gear rack is transmitted sinusoidally to thesecond arcing contact.

In conventional corner gears, the second arcing contact driven in theopposite direction is coupled with the complete travel of the firstdriven arcing contact either permanently or only temporarily using alow-precision ratchet gear.

SUMMARY

An object of the present invention is to design the corner gears sothat, when the first driving arcing contact engages positively with thesecond arcing contact driven in the opposite direction, the secondarcing contact is driven only along part of the contact travel, allowingthe second arcing contact driven in the opposite direction to pass adefined maximum speed at a predetermined point during this drivingphase.

According to the present invention, this object is achieved by designingthe rod-like driving element as a coupling rod having a journalpositioned transversely to the direction of thrust, and providing thecorner gears with a two-arm control lever having two stable endpositions, with one of its two ends being designed in the shape of afork for connecting-link type guidance of the journal, and the other endbeing pivoted on the second arcing contact via a reciprocating element.This reciprocating element can be a connecting rod or a journal thatengages with a slot in the second arcing contact.

A corner gear embodiment of this type is characterized by fewer,simpler, and lighter-weight components so that the corner gears have alow mass and form a self-contained unit that can have a flat design,therefore not hindering the flow of insulating gas (waste gas) that isproduced in the stationary permanent-current contact during switching.The corner gears also have a transmission ratio that varies duringactuation, is designed in the form of a sinusoidal half wave and itsmaximum can exceed 1:1, i.e., the second arcing contact being driven inthe opposite direction can be moved at a higher speed than the firstarcing contact during the decisive phase of contact opening (phase ofcontact separation and increasing distance between contacts). To achievethis, the corner gears are suitably designed so that the coupling rod isinserted into a guideway fastened to the stationary permanent-currentcontact. The fulcrum of the two-armed control lever is located betweenthe thrust connecting rod and the axis of the second arcing contact andis also connected to the stationary permanent-current contact. Thetwo-armed control lever is also positioned at an angle to the thrust rodand to the axis of the second arcing contact when in its stable endpositions. The fork-shaped end of the control lever is additionallyprovided with a longitudinal, open-ended cut-out between the two tines.The further journal located on the other end of the control lever isalso positioned transversely to the direction of coupling rod travel,with the slot with which this journal engages being located in a headpiece provided on the second arcing contact. The head piece, in turn, isguided in an axial direction along with the stationary portion of thejournal bearing connected to the sliding contact. The fork-like designof the one end of the control lever can provide an open-ended cut-outthat is designed so that the inward and outward axial movement into andout of the second arcing contact takes place without impact. To ensuresecure guiding of the control lever in its three positions (open,moving, and closed) in a compact design, the thrust rod, according to afurther embodiment of the present invention, has a guideway that isprovided with a cut-out that clears the rotational range of thefork-shaped end of the control lever, and the two tines of theforkshaped end of the control lever are provided with flattened areas ontheir outer surfaces, allowing the control lever to rest against thebottom of the thrust rod when the control lever is in either of the twoend positions. To stabilize these two end positions, two stops are alsoattached to the stationary portion of the journal bearing, with one ofthe flattened areas on the control lever coming to rest against thesestops. This prevents control lever overshooting at the end of theengagement between the journal and the fork-shaped end of the controllever.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the assignment between the corner gears and the stationarypermanent-current contact of the high-voltage circuit breaker in one endposition, according to an example embodiment of the present invention,

FIG. 2 shows a cross-section of the corner gear arrangement according tothe present invention.

FIGS. 3 to 5 show the corner gears in two intermediate positions and theother end position of the control lever.

DETAILED DESCRIPTION

Based on FIG. 2 of European Patent No. 0 313 813, FIG. 1 shows a sectionof stationary permanent-current contact 5 of a high-voltage circuitbreaker into which projects axially driven permanent-current contact 4,with insulating nozzle 8 attached to it, and first axially driven arcingcontact 9. The lower half of FIG. 1 shows the closed position ofdrivable permanent-current contact 4, while the upper half shows theopen position of insulating nozzle 8. In the closed position, insulatingnozzle 8 also surrounds second arcing contact 7 being driven in theopposite direction. Rod-type driving element 27 is attached toinsulating nozzle 8, with driving element 27 being designed in this caseas a coupling rod rather than a gear rack and having a journal 28 fordriving corner gears that is located transversely to the traveldirection of coupling rod 27, which has a U-shaped cross-section. Thecoupling rod can also have an L- or T-shaped cross-section, with eachcross-sectional part forming one guideway for guiding the coupling rod.In the embodiment, bottom 34 of the U-shaped cross-section forms theguideway.

Unlike the conventional designs, coupling rod 27 shown in FIG. 2 isinserted into two bearing walls 31 which form part of a housing 30. Thishousing is attached to a contact bridge 32, which is connected tostationary permanent-current contact 5 and carries stationary portion 33of a tubular sliding contact, in which second arcing contact 7 driven inthe opposite direction is contacted via contact plates. The end ofsecond arcing contact 7 facing away from the arcing contact gap isprovided with a flat head piece 13 that is inserted into two guideways35 formed by bearing walls 31 of housing 30. Flat head piece 13 isprovided with a slot 12 positioned vertically to coupling rod 27.

A two-armed control lever 10, one end of which is shaped like a fork andthe other end is provided with a journal 11, is located in housing 30 onan axis 28 positioned vertically to the plane of the drawing. Journal 11engages with slot 12 in head piece 13. The forked end has two tines 16and 17 that surround an open-ended orifice 18 with which journal 28 ofcoupling rod 27 can engage. On the outside both tines 16 and 17 areprovided with a seating surface 19 and 20, respectively, with whichcontrol lever 10, depending on its position can rest against bottom 24of the U-shaped cross-sectional profile of coupling rod 27. Stops 36 and37 in housing 30 ensure that control lever 10 remains in the correctrest position. Both rest positions represent end positions between whichcontrol lever 10 moves under the influence of journal 28. To enable thefork-shaped end to rotate around axis 38, coupling rod 27 must beprovided with a longitudinal slot 29 in bottom 24 of the U-shapedcross-section.

When a tripping movement is performed, coupling rod 27, and thus journal28, passes continuously through different intermediate positions,starting from the position illustrated in FIG. 1, with FIGS. 2 and 3showing those intermediate positions that head piece 13—and thuscorresponding arcing contact 7 moving in the opposite direction—assumesshortly before and shortly after reaching the maximum speed, while FIG.5 shows the other end position of control lever 10. Following theposition shown in FIG. 5, the coupling rod can move back to the left,without control lever 10 having to change its position.

What is claimed is:
 1. A high-voltage circuit breaker, comprising: afirst axially drivable permanent-current contact; a second stationarypermanent-current contact; first and second arcing contacts axiallysurrounded by the first and second permanent-current contacts, the firstand second arcing contacts positioned coaxially and opposite withrespect to one another; an insulating nozzle permanently connected toboth the first permanent-current contact and the first arcing contact; asliding contact guiding the second arcing contact; a reciprocatingelement; corner gears including a two-armed control lever having twostable end positions, a first end of the control lever being shaped likea fork, a second end of the control lever being pivoted on the secondarcing contact via the reciprocating element; and a rod-type drivingelement attached to the insulating nozzle and positioned parallel of thesecond arcing contact using the corner gears, a driving movement of thefirst permanent-current contact for driving the first and second arcingcontacts in opposite directions being transmitted to the second arcingcontact via the driving element, the driving element including acoupling rod having a journal positioned transversely to a direction oftravel of the coupling rod, the first end of the control lever providingconnecting-link type guidance of the journal.
 2. The high-voltagecircuit breaker according to claim 1, wherein the reciprocating elementincludes a further journal at the second end of the control lever, andwherein the second arcing contact has a slot with which the furtherjournal engages.
 3. The high-voltage circuit breaker according to claim1, wherein the second permanent-current contact includes a guideway, thecoupling rod being guided on the guideway; wherein a fulcrum of thecontrol lever is located between the coupling rod and an axis of thesecond arcing contact, the fulcrum being permanently connected to thesecond permanent-current contact; wherein the control lever ispositioned at an angle to the coupling rod and the axis of the secondarcing contact when the control lever is in one of the stable endpositions; wherein the first end of the control lever has alongitudinal, open-ended cutout between two tines; and wherein a furtherjournal is positioned transversely to the direction of travel of thecoupling rod.
 4. The high-voltage circuit breaker according to claim 1,wherein the coupling rod has a guideway that is provided with an orificefor clearing a rotation range of the first end of the control lever; andwherein two tines of the first end of the control lever includeflattened areas on an outer surface which allow the control lever torest against the guideway of the coupling rod when the control lever isin either of the two end positions.